Cutter bit for roof drill



June 8, 1965 A. B. BOWER, JR 3,187,825

CUTTER BIT FOR ROOF DRILL Filed Aug. 6, 1963 lnven/or: Q Arno/d B. Bower, Jr /5 A k by His Afro/nay- United States Patent 3,187,825 CUTTER BIT FOR ROOF DRILL Arnold B. Bower, Jr., St. Clair Shores, Mich., assignor to General Electric Company, a corporation of New York Filed Aug. 6, 1963, Ser. No. 300,216 1 Claim. (Cl. 175-327) This invention relates to a cutter bit for a roof drill and, more specifically, to a cutter bit and to a cutter bit assembly for use in roof drilling in mines where it is necessary to collect and remove dust and rock particles during the drilling operation.

In the drilling of holes in the roof of a mine for the purpose of installing bolts to be used for the support of the mine roof during mining operations, it is usually necessary to collect the removed material in the form of dust and rock particles to prevent contamination of the atmosphere and its resulting hazards to the miner. The two most widely used methods of dust collection employ suction devices which form an integral part of the composite roof drill. The two devices, commonly referred to as external and through-the-steel types, respectively, and described in greater detail hereinafter, require cutter bits of difierent shank length because the means of attachment of the cutter bit is necessarily located at different positions in the two different systems of dust collection. The result is that two difierent types of cutter bits must be manufactured for the same roof drilling operation. Mining companies which use both types of dust collection units must stock two different roof hits as the miner cannot use the two bits interchangeably.

It is a primary object of this invention to provide a cutter bit which may be used interchangeably in the most common types of dust collecting units in roof drilling.

It is an additional object of this invention to provide a cutter bit assembly having a removable cutter bit which may be securely attached to a drill and efiiciently used in roof drilling, regardless of the particular type of dust collector unit employed.

The invention will be more clearly understood from the following description taken in connection with the accompanyin g drawing in which:

FIGURE 1 is an exploded perspective view of a cutter bit assembly for use in a through-the-steel type dust collection unit illustrating one embodiment of the invention;

FIGURE 2 is an assembled view partly in vertical section of the cutter bit assembly of FIG. 1;

FIGURE 3 is an exploded perspective view of a cutter bit assembly for use in an external type dust collector system; and

FIGURE 4 is an assembled view partly in vertical section of the cutter bit assembly of FIG. 3.

Briefly stated, the invention involves a cutter bit for a roof drill in which the cutter bit shank has a first portion adjacent the head of the cutter bit of polygonal radial cross section and a second portion extending therefrom of reduced radial cross section. Within the polygonal portion of the shank of the cutter bit, there are one or more radial apertures adapted to receive a locking pin for attaching the cutter bit to through-the-steel dust collector units. Within the second portion of the shank, there is an additional aperture to receive a locking pin for attachment of the cutter bit to an external type dust collector.

Referring to the drawing, the cutter bit 1 has a head 3,187,825 Patented June 8, 1965 ice.

portion 2, a shank portion 3 and a flat projecting tang 4. The cutter head may be of any conventional shape ordinarily used for roof drilling in mines. The cutter head illustrated in the drawing has a cemented carbide cutting insert 5 brazed to the inner opposite faces of cutter head 2 so that the insert extends across the body of the cutting head. For square seating on the dust collector, the bottom surface or shoulder 6 is fiat at the plane of attachment of the head to the shank. Shank 3 contains apertures 7 and 8 and tang 4 contains aperture 9. Tang 4 extends along a plane which projects axially and diagonally from two opposite corners of square shank 3. Thus, the tang is at a 45 angle to each of the sides of shank 3. This affords maximum width, and thus strength, for tang 4 without extending its width beyond that of shank 3.

The drawing illustrates the two types of cutter bit assemblies ordinarily used for dust collection in roof drilling operations. The cutter bit assembly of FIGS. 1 and 2 is for through-the-steel type dust collection. Dust collector casing 10 possesses an axial bore 11 of square radial cross section to receive shank 3 and tang 4 of cutter bit 1. Casing 10 is coupled to cutter bit 1 by the insertion of a locking pin 12 through an aperture 13 in the casing and the aligned aperture 7 (or 8) in the shank of the cutter bit. During drilling operations, dust or other removed material is forced by suction into openings 14 located at opposite sides of casing 10 and removed through the hollow interior 15 of the casing and thence through the driving unit to a suitable collection unit.

FIGS. 3 and 4 illustrate an external type dust collector in which dust is collected externally of the cutter bit assembly. Cutter bit 1 is inserted in axial bore 16 in dust collector casing 17 and locked in place by insertion of locking pin 18 through aperture 19 in casing 17 and aligned aperture 9 in tang 4 of the shank of the cutter bit. Helical ledge 20 extends along the external surface of casing 17 for conveying the dust away from the mine roof. A roof drill using an external type dust collection system of this type is shown, for example, at page of Mining Congress Journal, November 1956. In operation, a collar of hollow metal is placed with one extremity at the roof of the mine and is attached at its other extremity to a vacuum device which creates a suction in the collar. The cutter bit assembly of FIGS. 3 and 4 is inserted into the collar. During drilling, the dust is conveyed down the helical ledge and is removed by the suction created between the collar and the cutter bit assembly and suitably collected.

Previous practice required the cutter bit manufacturer i to forge a cutter bit having a shank of suf icient length to receive a locking pin for attachment to an external type dust collector casing (FIGS. 3 and 4). A portion of this shank was then necessarily cut otf for use in throughthe-steel type dust collection in order to allow the free flow of dust into the opening (numeral 14, FIG. 2) of through-the-steel casings. The presentinvention makes possible the use of a single interchangeable cutter bit which may be securely and firmly mounted in a drill, regardless of which system of dust removal and collection is utilized. As can be seen from FIG. 2, the shape of the tang and its manner of projection from the shank of the cutter bit are such that it does not interfere with the entrance of removed material or dust through opening 14 in through-the-steel type dust collector units. Yet, the tang is of sufticient length and strength to enable it to lock securely the cutter bit in' place in external dust collector units as shown in FIG. 4.

What I claim as new and desire to secure by Letters Patent of the United States is:

A removable cutter bit for a roof drill comprising a cutter head and a shank, said shank having a first portion adjacent the cutter head of polygonal cross section and a substantially fiat tang of reduced cross section extending vertically and diagonally from said square portion, said first portion of the shank and said tang each having radial apertures therethrough adapted to receive a locking pin for coupling said cutter bit through one of said apertures to a roof drill.

7 References Cited by the Examiner UNITED STATES PATENTS 10 CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN BENDETT, Examiner. 

